Retinal Photoreceptor Cells Research Articles

Ccrk-Mak/Ick signaling is a ciliary transport regulator essential for retinal photoreceptor survival.

Primary cilia are microtubule-based sensory organelles whose dysfunction causes ciliopathies in humans. The formation, function, and maintenance of primary cilia depend crucially on intraflagellar transport (IFT); however, the regulatory mechanisms of IFT at ciliary tips are poorly understood. Here, we identified that the ciliopathy kinase Mak is a ciliary tip-localized IFT regulator that cooperatively acts with the ciliopathy kinase Ick, an IFT regulator. Simultaneous disruption of Mak and Ick resulted in loss of photoreceptor ciliary axonemes and severe retinal degeneration. Gene delivery of Ick and pharmacological inhibition of FGF receptors, Ick negative regulators, ameliorated retinal degeneration in Mak -/- mice. We also identified that Ccrk kinase is an upstream activator of Mak and Ick in retinal photoreceptor cells. Furthermore, the overexpression of Mak, Ick, and Ccrk and pharmacological inhibition of FGF receptors suppressed ciliopathy-related phenotypes caused by cytoplasmic dynein inhibition in cultured cells. Collectively, our results show that the Ccrk-Mak/Ick axis is an IFT regulator essential for retinal photoreceptor maintenance and present activation of Ick as a potential therapeutic approach for retinitis pigmentosa caused by MAK mutations.

Bile duct ligation impairs visual acuity in rats by ammonia- and bilirubin-induced retinal degeneration.

Patients with hepatic failure are often accompanied by hepatic retinopathy, but the cellular and molecular mechanisms underlying the hepatic retinopathy remain unclear. In this study, we investigated how liver failure leads to hepatic retinopathy using bile duct ligation (BDL) rats as a cholestasis animal model. Light-dark box test was used to assess sensitivity to light, indexed as visual acuity. On D28 post-BDL, rats were subjected to light-dark box test and blood samples were collected for biochemical analyses. The rats then were euthanized. Liver, spleen and both side of eye were quickly harvested. We showed that BDL impaired rat sensitivity to light, significantly decreased the thickness of inner nuclear layer (INL), outer nuclear layer (ONL) and total retina, as well as the retinal cell numbers in ONL and ganglion cell layer (GCL). The expression of rhodopsin (RHO), brn-3a and GPX4 was significantly decreased in retina of BDL rats, whereas the expression of cleaved caspase 3, 8, 9, bax/bcl-2, RIP1, GFAP, and iba-1, as well as TUNEL-positive cells were significantly increased. In cultured retinal explant, we found that NH4Cl (0.2, 1, 5 mM) concentration-dependently impaired activity of retinal explant, decreased thickness of INL and ONL, downregulated expression of brn-3a, RHO and GFAP, increased expression of cl-caspase 3 and TUNEL-positive cell numbers, with NH4Cl (5 mM) almost completely disrupting the structure of the cultured retina; bilirubin (1 μM) significantly upregulated GFAP expression, whereas high level (10 μM) of bilirubin downregulated expression of GFAP. We further demonstrated in vivo that hyperammonemia impaired rat sensitivity to light, decreased thickness of INL and ONL, downregulated expression of RHO, brn-3a, GFAP and increased expression of cl-caspase 3; hyperbilirubinemia impaired rat sensitivity to light, upregulated expression of GFAP and iba-1. In conclusion, BDL impaired rat visual acuity due to the elevated levels of ammonia and bilirubin. Ammonia induced loss of retinal ganglion cells and rod photoreceptor cells via apoptosis-mediated cell death. Bilirubin impaired retinal function via activating microglia and Müller cells.

Rhodium nanozyme mitigates RPE degeneration and preserves vision in age-related macular degeneration via antioxidant and anti-inflammatory mechanisms

Age-related macular degeneration (AMD) is the leading cause of blindness among elderly people worldwide. However, there are currently no effective treatments for AMD. Oxidative stress-induced retinal pigment epithelium (RPE) degeneration and the inflammatory response are the main causes of AMD. In this study, a polyethylene glycol (PEG)-coated rhodium nanozyme (PEG-RhZ) with excellent reactive oxygen species (ROS) and reactive nitrogen species (RNS) elimination capability was synthesized for the treatment of AMD. PEG-RhZs protected RPE cell viability and barrier function upon exposure to oxidative stress stimuli. Additionally, microglial migration and iNOS, IL-1β and TNF-α expression were inhibited by PEG-RhZs. In the acute phase of the AMD model, PEG-RhZs significantly alleviated RPE oxidative damage and inhibited microglial activation. In the late stage of the AMD model, PEG-RhZs reduced photoreceptor loss and improved vision impairment. Furthermore, PEG-RhZs showed good biocompatibility and stability both in vitro and in vivo. Collectively, our findings suggest the therapeutic potential of PEG-RhZs for AMD treatment.STATEMENT OF SIGNIFICANCE: AMD is a kind of retinal degenerative disease that poses heavy health burden globally. PEG-RhZs exhibiting robust ROS and RNS scavenging capabilities have shown promise in safeguarding retinal pigment epithelium (RPE) from oxidative stress, suppressing microglia activation and the secretion of pro-inflammatory molecules, mitigating loss of retinal photoreceptor cells, and ameliorating visual impairment. The commendable antioxidant properties, biological safety, and biostability of PEG-RhZs offer valuable insights for the clinical management of AMD.

Low-error, high-speed, and large-scale hardware implementation of retinal photoreceptor cells: Cone and rod cells

In recent times, there has been a significant focus on creating prosthetics and medical interventions to aid in the treatment of diseases, recovery, and the improvement of biological functions. Researchers have particularly directed their attention toward developing hardware models for delicate biological parts such as the brain, heart, nervous system, and. One area of particular interest is the retina, which is the thinnest and innermost layer of the eye. This research paper focuses on the development of a high-speed and low-error hardware implementation for retinal cone and rod cells. Current mathematical models often use multiple nonlinear functions to describe the behavior of these cells. However, these nonlinear functions can sometimes be limiting in terms of speed. In this study, we explore the use of trigonometric functions to approximate the non-linear properties of retinal cone and rod cells, allowing for improved performance. The results of the simulation show that the suggested model is in line with the functioning of primary cone and rod cells, particularly in relation to time characteristics, dynamic response, and margin of error. By implementing the proposed model in Large-Scale (300 cell) on a Virtex-5 Field Programmable Gate Array (FPGA) board, notable benefits were observed. One of these advantages includes increasing the synthesis frequency of the proposed model by 3.35 and 3.44 times faster than the original model for the cone cell and rod cell, respectively. Another advantage is the ability to implement 300 cells of the proposed models on the FPGA, compared to the implementation of a single cell of the original models, with only a two-fold increase in the amount of hardware resources used. The proposed framework is legitimate and features a compact hardware size and suitable network frequency, as demonstrated by the outcomes from implementing the hardware on the Virtex-5 reconfigurable board (FPGA).

Magnetically Guided Adeno-Associated Virus Delivery for the Spatially Targeted Transduction of Retina in Eyes.

Adeno-associated viruses (AAVs) are intensively explored for gene therapies in general and have found promising applications for treating retina diseases. However, controlling the specificity (tropism) and delivery of AAVs to selected layers, cell types, and areas of the retina is a major challenge to further develop retinal gene therapies. Magnetic nanoparticles (MNPs) provide effective delivery platforms to magnetically guide therapeutics to target cells. Yet, how MNPs can deliver AAVs to transfect particular retina layers and cells remains elusive. Here, it is demonstrated that MNPs can be used to transport different AAVs through the retina and to modulate the selective transduction of specific retinal layers or photoreceptor cells in ex vivo porcine explants and whole eyes. Thereby, transduction is triggered by bringing the viruses in close proximity to the target cell layer and by controlling their interaction time. It is shown that this magnetically guided approach to transport AAVs to selected areas and layers of the retina does not require the cell-specific optimization of the AAV tropism. It is anticipated that the new approach to control the delivery of AAVs and to selectively transduce cellular systems can be applied to many other tissues or organs to selectively deliver genes of interest.

The correlation of caspase-3 expression with retinal ganglion and photoreceptor cell densities in diabetic retinopathy

The correlation of caspase-3 expression with retinal ganglion and photoreceptor cell densities in diabetic retinopathy

Sulforaphane and ophthalmic diseases.

Sulforaphane (SFN) is an organosulfur compound categorized as an isothiocyanate (ITC), primarily extracted from cruciferous vegetables like broccoli and cabbage. The molecular formula of sulforaphane (SFN) is C6H11NOS2. SFN is generated by the hydrolysis of glucoraphanin (GRP) through the enzyme myrosinase, showing notable properties including anti-diabetic, anti-inflammatory, antimicrobial, anti-angiogenic, and anticancer attributes. Ongoing clinical trials are investigating its potential in diseases such as cancer, neurodegenerative diseases, diabetes-related complications, chronic kidney disease, cardiovascular disease, and liver diseases. Several animal carcinogenesis models and cell culture models have shown it to be a very effective chemopreventive agent, and the protective effects of SFN in ophthalmic diseases have been linked to multiple mechanisms. In murine models of diabetic retinopathy and age-related macular degeneration, SFN delays retinal photoreceptor cell degeneration through the Nrf2 antioxidative pathway, NF-κB pathway, AMPK pathway, and Txnip/mTOR pathway. In rabbit models of keratoconus and cataract, SFN has been shown to protect corneal and lens epithelial cells from oxidative stress injury by activating the Keap1-Nrf2-ARE pathway and the Nrf-2/HO-1 antioxidant pathway. Oral delivery or intraperitoneal injection at varying concentrations are the primary strategies for SFN intake in current preclinical studies. Challenges remain in the application of SFN in eye disorders due to its weak solubility in water and limited bioavailability because of the presence of blood-ocular barrier systems. This review comprehensively outlines recent research on SFN, elucidates its mechanisms of action, and discusses potential therapeutic benefits for eye disorders such as age-related macular degeneration (AMD), diabetic retinopathy (DR), cataracts, and other ophthalmic diseases, while also indicating directions for future clinical research to achieve efficient SFN treatment for ophthalmic diseases.

Neuroplasticity of visual brain network induced by hypoxia.

The effects of hypoxia on brain function remain largely unknown. This study aimed to clarify this issue by visual-stimulated functional magnetic resonance imaging design. Twenty-three college students with a 30-d high-altitude exposure were tested before, 1week and 3months after returning to sea level. Brain functional magnetic resonance imaging and retinal electroretinogram were acquired. One week after returning to sea level, decreased blood oxygenation level dependent in the right lingual gyrus accompanied with increased blood oxygenation level dependent in the frontal cortex and insular cortex, and decreased amplitude of electroretinogram a-wave in right eye; moreover, the bilateral lingual gyri showed increased functional connectivity within the dorsal visual stream pathway, and the blood oxygenation level dependent signals in the right lingual gyrus showed positive correlation with right retinal electroretinogram a-wave. Three months after returning to sea level, the blood oxygenation level dependent signals recovered to normal level, while intensively increased blood oxygenation level dependent signals in a broad of brain regions and decreased retinal electroretinogram were also existed. In conclusion, hypoxic exposure has long-term effects on visual cortex, and the impaired retinal electroretinogram may contribute to it. The increased functional connectivity of dorsal stream may compensate for the decreased function of retinal photoreceptor cells to maintain normal visual function.

Development of TRIB3-Based Therapy as a Gene-Independent Approach to Treat Retinal Degenerative Disorders.

Inherited retinal degeneration (RD) constitutes a heterogeneous group of genetic retinal degenerative disorders. The molecular mechanisms underlying RD encompass a diverse spectrum of cellular signaling, with the unfolded protein response (UPR) identified as a common signaling pathway chronically activated in degenerating retinas. TRIB3 has been recognized as a key mediator of the PERK UPR arm, influencing various metabolic pathways, such as insulin signaling, lipid metabolism, and glucose homeostasis, by acting as an AKT pseudokinase that prevents the activation of the AKT → mTOR axis. This study aimed to develop a gene-independent approach targeting the UPR TRIB3 mediator previously tested by our group using a genetic approach in mice with RD. The goal was to validate a therapeutic approach targeting TRIB3 interactomes through the pharmacological targeting of EGFR-TRIB3 and delivering cell-penetrating peptides targeting TRIB3 → AKT. The study employed rd10 and P23H RHO mice, with afatinib treatment conducted in p15 rd10 mice through daily intraperitoneal injections. P15 P23H RHO mice received intraocular injections of cell-penetrating peptides twice at a 2-week interval. Our study revealed that both strategies successfully targeted TRIB3 interactomes, leading to an improvement in scotopic A- and B-wave ERG recordings. Additionally, the afatinib-treated mice manifested enhanced photopic ERG amplitudes accompanied by a delay in photoreceptor cell loss. The treated rd10 retinas also showed increased PDE6β and RHO staining, along with an elevation in total PDE activity in the retinas. Consequently, our study demonstrated the feasibility of a gene-independent strategy to target common signaling in degenerating retinas by employing a TRIB3-based therapeutic approach that delays retinal function and photoreceptor cell loss in two RD models.

Optical Coherence Tomography in Inherited Macular Dystrophies: A Review.

Macular dystrophies (MDs) constitute a collection of hereditary retina disorders leading to notable visual impairment, primarily due to progressive macular atrophy. These conditions are distinguished by bilateral and relatively symmetrical abnormalities in the macula that significantly impair central visual function. Recent strides in fundus imaging, especially optical coherence tomography (OCT), have enhanced our comprehension and diagnostic capabilities for MD. OCT enables the identification of neurosensory retinal disorganization patterns and the extent of damage to retinal pigment epithelium (RPE) and photoreceptor cells in the dystrophies before visible macular pathology appears on fundus examinations. It not only helps us in diagnostic retinal and choroidal pathologies but also guides us in monitoring the progression of, staging of, and response to treatment. In this review, we summarize the key findings on OCT in some of the most common MD.

AAV2-PDE6B restores retinal structure and function in the retinal degeneration 10 mouse model of retinitis pigmentosa by promoting phototransduction and inhibiting apoptosis.

JOURNAL/nrgr/04.03/01300535-202508000-00030/figure1/v/2024-09-30T120553Z/r/image-tiff Retinitis pigmentosa is a group of inherited diseases that lead to retinal degeneration and photoreceptor cell death. However, there is no effective treatment for retinitis pigmentosa caused by PDE6B mutation. Adeno-associated virus (AAV)-mediated gene therapy is a promising strategy for treating retinitis pigmentosa. The aim of this study was to explore the molecular mechanisms by which AAV2-PDE6B rescues retinal function. To do this, we injected retinal degeneration 10 (rd10) mice subretinally with AAV2-PDE6B and assessed the therapeutic effects on retinal function and structure using dark- and light-adapted electroretinogram, optical coherence tomography, and immunofluorescence. Data-independent acquisition-mass spectrometry-based proteomic analysis was conducted to investigate protein expression levels and pathway enrichment, and the results from this analysis were verified by real-time polymerase chain reaction and western blotting. AAV2-PDE6B injection significantly upregulated PDE6β expression, preserved electroretinogram responses, and preserved outer nuclear layer thickness in rd10 mice. Differentially expressed proteins between wild-type and rd10 mice were closely related to visual perception, and treating rd10 mice with AAV2-PDE6B restored differentially expressed protein expression to levels similar to those seen in wild-type mice. Kyoto Encyclopedia of Genes and Genome analysis showed that the differentially expressed proteins whose expression was most significantly altered by AAV2-PDE6B injection were enriched in phototransduction pathways. Furthermore, the phototransduction-related proteins Pde6α, Rom1, Rho, Aldh1a1, and Rbp1 exhibited opposite expression patterns in rd10 mice with or without AAV2-PDE6B treatment. Finally, Bax/Bcl-2, p-ERK/ERK, and p-c-Fos/c-Fos expression levels decreased in rd10 mice following AAV2-PDE6B treatment. Our data suggest that AAV2-PDE6B-mediated gene therapy promotes phototransduction and inhibits apoptosis by inhibiting the ERK signaling pathway and upregulating Bcl-2/Bax expression in retinitis pigmentosa.

WNT-inhibitory factor 1-mediated glycolysis protects photoreceptor cells in diabetic retinopathy

BackgroundIn diabetic retinopathy (DR), hypoxia-inducible factor (HIF-1α) induces oxidative stress by upregulating glycolysis. This process leads to neurodegeneration, particularly photoreceptor cell damage, which further contributes to retinal microvascular deterioration. Further, the regulation of Wnt-inhibitory factor 1 (WIF1), a secreted Wnt signaling antagonist, has not been fully characterized in neurodegenerative eye diseases. We aimed to explore the impact of WIF1 on photoreceptor function within the context of DR.MethodTwelve-week-old C57BL/KsJ-db/db mice were intravitreally injected with WIF1 overexpression lentivirus. After 4 weeks, optical coherence tomography (OCT), transmission electron microscopy (TEM), H&E staining, and electroretinography (ERG) were used to assess the retinal tissue and function. The potential mechanism of action of WIF1 in photoreceptor cells was explored using single-cell RNA sequencing. Under high-glucose conditions, 661 W cells were used as an in vitro DR model. WIF1-mediated signaling pathway components were assessed using quantitative real-time PCR, immunostaining, and western blotting.ResultTypical diabetic manifestations were observed in db/db mice. Notably, the expression of WIF1 was decreased at the mRNA and protein levels. These pathological manifestations and visual function improved after WIF1 overexpression in db/db mice. TEM demonstrated that WIF1 restored damaged mitochondria, the Golgi apparatus, and photoreceptor outer segments. Moreover, ERG indicated the recovery of a-wave potential amplitude. Single-cell RNA sequencing and in vitro experiments suggested that WIF1 overexpression prevented the expression of glycolytic enzymes and lactate production by inhibiting the canonical Wnt signaling pathway, HIF-1α, and Glut1, thereby reducing retinal and cellular reactive oxygen species levels and maintaining 661 W cell viability.ConclusionsWIF1 exerts an inhibitory effect on the Wnt/β-catenin-HIF-1α-Glut1 glycolytic pathway, thereby alleviating oxidative stress levels and mitigating pathological structural characteristics in retinal photoreceptor cells. This mechanism helps preserve the function of photoreceptor cells in DR and indicates that WIF1 holds promise as a potential therapeutic candidate for DR and other neurodegenerative ocular disorders.Graphical

Potential therapeutic agent for the treatment of retinal detachment: Artificial interphotoreceptor matrix

Retinal detachment (RD) is a common ophthalmic emergency that presents as a separation and gap between the retinal neuroepithelium and the pigment epithelium that supplies the retina. Treatment for RD is primarily focused on surgically reattaching the retina as soon as possible. Nevertheless, the recovery of visual function in patients undergoing surgical retina reattachment of the retina is insufficient. Previous studies' findings revealed that photoreceptor cell death was not sufficiently prevented by surgically reattaching the retina. Besides, intervention with the retinal microenvironment has been proposed as a ground-breaking opinion in the treatment of RD to further preserve the patient's visual function. Further, traditional vitrectomy invariably replaces the interphotoreceptor matrix (IPM) in its original physiological form with leftover fluid in the possible interstitial space of the subretinal cavity. As a result, the leftover fluid might cause oxidative stress and inflammatory reactions that can hinder the functional recovery and nutrition delivery of retinal photoreceptor cells. In this context, the present hypotheses pioneered an artificial interphotoreceptor matrix (AIPM) as a secure and economical solution. In this article, we explain how surgical procedures and gas–liquid exchange will temporarily replace the natural IPM with AIPM in the subretinal cavity. Also, a cocktail of medications to suppress oxidative stress and inflammatory reactions as well as prevent apoptosis will be present in the AIPM. Under comprehensive consideration, we summarized the evidence that is currently available in the field, including several studies that showed potentially useful medications in RD examinations. We evaluated the experimental and anticipated outcomes to construct an AIPM and validate it. In conclusion, we offer an evaluation, viewpoint, and discussion of the substantial significance of AIPM as well as potential clinical applications.

Bioinspired Photoreceptors with Neural Network for Recognition and Classification of Sign Language Gesture.

This work addresses the design and implementation of a novel PhotoBiological Filter Classifier (PhBFC) to improve the accuracy of a static sign language translation system. The captured images are preprocessed by a contrast enhancement algorithm inspired by the capacity of retinal photoreceptor cells from mammals, which are responsible for capturing light and transforming it into electric signals that the brain can interpret as images. This sign translation system not only supports the effective communication between an agent and an operator but also between a community with hearing disabilities and other people. Additionally, this technology could be integrated into diverse devices and applications, further broadening its scope, and extending its benefits for the community in general. The bioinspired photoreceptor model is evaluated under different conditions. To validate the advantages of applying photoreceptors cells, 100 tests were conducted per letter to be recognized, on three different models (V1, V2, and V3), obtaining an average of 91.1% of accuracy on V3, compared to 63.4% obtained on V1, and an average of 55.5 Frames Per Second (FPS) in each letter classification iteration for V1, V2, and V3, demonstrating that the use of photoreceptor cells does not affect the processing time while also improving the accuracy. The great application potential of this system is underscored, as it can be employed, for example, in Deep Learning (DL) for pattern recognition or agent decision-making trained by reinforcement learning, etc.

Inhibition of Ferroptosis Ameliorates Photoreceptor Degeneration in Experimental Diabetic Mice

Diabetic retinopathy (DR) is a leading cause of vision impairment in the working-age population worldwide. Various modes of photoreceptor cell death contribute to the development of DR, including apoptosis and autophagy. However, whether ferroptosis is involved in the pathogenesis of photoreceptor degeneration in DR is still unclear. High-glucose (HG)-stimulated 661W cells and diabetic mice models were used for in vitro and in vivo experiments, respectively. The levels of intracellular iron, glutathione (GSH), reactive oxygen species (ROS), lipid peroxidation (MDA), and ferroptosis-related proteins (GPX4, SLC7A11, ACSL4, FTH1, and NCOA4) were quantified to indicate ferroptosis. The effect of ferroptosis inhibition was also assessed. Our data showed the levels of iron, ROS, and MDA were enhanced and GSH concentration was reduced in HG-induced 661W cells and diabetic retinas. The expression of GPX4 and SLC7A11 was downregulated, while the expression of ACSL4, FTH1, and NCOA4 was upregulated in the 661W cells cultured under HG conditions and in the photoreceptor cells in diabetic mice. Furthermore, the administration of the ferroptosis inhibitor ferrostatin-1 (Fer-1) obviously alleviated ferroptosis-related changes in HG-cultured 661W cells and in retinal photoreceptor cells in diabetic mice. Taken together, our findings suggest that ferroptosis is involved in photoreceptor degeneration in the development of the early stages of DR.

Deferoxamine attenuates visual impairment in retinal ischemia‒reperfusion via inhibiting ferroptosis

Retinal ischemia‒reperfusion (I/R) injury can cause significant damage to human retinal neurons, greatly compromising their functions. Existing interventions have been proven to have little effect. Ferroptosis is a newly discovered type of programmed cell death that has been found to be involved in the process of ischemia‒reperfusion in multiple organs throughout the body. Studies have shown that it is also present in retinal ischemia‒reperfusion injury. A rat model of retinal ischemia‒reperfusion injury was constructed and treated with deferoxamine. In this study, we found the accumulation of Fe2+, reactive oxygen species (ROS), malondialdehyde (MDA), and the consumption of glutathione (GSH) via ELISA testing; increased expression of transferrin; and decreased expression of ferritin, SLC7A11, and GPX4 via Western blotting (WB) and real-time PCR testing. Structural signs of ferroptosis (mitochondrial shrinkage) were observed across multiple cell types, including retinal ganglion cells (RGCs), photoreceptor cells, and pigment epithelial cells. Changes in visual function were detected by F-VEP and ERG. The results showed that iron and oxidative stress were increased in the retinal ischemia‒reperfusion injury model, resulting in ferroptosis and tissue damage. Deferoxamine protects the structural and functional soundness of the retina by inhibiting ferroptosis through the simultaneous inhibition of hemochromatosis, the initiation of transferrin, and the degradation of ferritin and activating the antioxidant capacity of the System Xc-GSH-GPX4 pathway.

Unlocking the role of lactate: metabolic pathways, signaling, and gene regulation in postmitotic retinal cells.

The Warburg effect, which was first described a century ago, asserts that mitotic tumor cells generate higher quantities of lactate. Intriguingly, even in typical physiological circumstances, postmitotic retinal photoreceptor cells also produce elevated levels of lactate. Initially classified as metabolic waste, lactate has since gained recognition as a significant intracellular signaling mediator and extracellular ligand. This current review endeavors to provide a concise overview and discourse on the following topics: the localization of lactate-producing enzymes, the functional significance of these enzymes, the signaling functions of lactate, and its impact on the gene expression of photoreceptors in retinal cells.

Qi-Shen-Tang alleviates retinitis pigmentosa by inhibiting ferroptotic features via the NRF2/GPX4 signaling pathway

Ferroptosis has been observed during retinal photoreceptor cell death, suggesting that it plays a role in retinitis pigmentosa (RP) pathogenesis. Qi-Shen-Tang (QST) is a combination of two traditional Chinese medicines used for the treatment of ophthalmic diseases; however, its mechanism of action in RP and ferroptosis remains unclear. Therefore, this study aimed to explore the effect and potential molecular mechanisms of QST on RP. QST significantly improved tissue morphology and function of the retina in the RP model mice. A significant increase in retinal blood flow and normalization of the fundus structure were observed in mice in the treatment group. After QST treatment, the level of iron and the production of malondialdehyde decreased significantly; the levels of superoxide dismutase and glutathione increased significantly; and the protein expression of glutathione peroxidase 4 (GPX4), glutathione synthetase, solute carrier family 7 member 11, and nuclear factor erythroid 2-related factor 2 (NRF2) increased significantly. The molecular docking results demonstrated potential interactions between the small molecules of QST and the key proteins of NRF2/GPX4 signaling pathway. Our results indicate that QST may inhibit ferroptosis by inhibiting the NRF2/GPX4 signaling pathway, thereby reducing RP-induced damage to retinal tissue.

Inhibition of photoreceptor apoptosis in mice with retinitis pigmentosa through NF-κB/NLRP3 pathway suppression with Lycium barbarum polysaccharide

ObjectiveTo explore whether Lycium barbarum polysaccharide (LBP) can reduce the apoptosis of retinal photoreceptor cells in retinitis pigmentosa (RP) mice by inhibiting nuclear factor-kappa B (NF-κB)/NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) signaling pathway. Methods(i) In vitro experiments, mouse retinal ganglion cells (661W cells) were divided into normal, model, LBP low-dose (LBP-L, 40 mg/L), LBP middle-dose (LBP-M, 80 mg/L), LBP high-dose (LBP-H, 160 mg/L), and positive drug control (NLRP3 inhibitor, 160 mg/L) groups. And the 661W cells were exposed to varying concentrations of H2O2 ranging from 50 to 400 μmol/L to determine the optimal concentration for inducing apoptosis (200 μmol/L). Then the cell viability was assessed using Cell Counting Kit-8 (CCK-8), while the apoptosis rate was detected by flow cytometry; the expression of NLRP3 was detected by immunofluorescence; and the expression of apoptosis markers was detected by enzyme-linked immunosorbent assay (ELISA) and Western blot (WB). (ii) In vivo assays were carried out with the use of C57/BL6 and Rd10 mice. The animal experimental groups were divided into normal, model, LBP-L, LBP-M, LBP-H, and NLRP3 inhibitor groups, in which the normal group was C57/BL6 mice and the other groups were Rd10 mice. Ten mice were included in each group, and the corresponding drugs were administered intragastrically for a duration of four weeks. NF-κB/NLRP3 pathway and the expression of apoptosis markers were observed by electroretinogram, histopathological examination, and WB to assess the effects of LBP on retinal photoreceptor cell apoptosis. Results(i) In vitro experiments, compared with the normal group, the apoptosis rate of 661W cells in model group was significantly increased (P < 0.01), and the expression levels of key proteins of NF-κB/NLRP pathway, such as NLRP3, NF-κB, p-NF-κB, and pro-apoptotic protein caspase-3, were up-regulated (P < 0.01). The rate of Bax/Bcl-2 was increased (P < 0.01), and the concentrations of interleukin (IL)-1β and tumor necrosis factor (TNF)-α were significantly increased (P < 0.01). Compared with the model group, high dose of LBP decreased the apoptosis rate of 661W cells (P < 0.01), and down-regulated the expression levels of the key proteins of NF-κB/NLRP3 pathway, including NF-κB, NLRP3, p-NF-κB, and caspase-3 (P < 0.01). The rate of Bax/Bcl-2 was decreased (P < 0.01), and the concentrations of IL-1β and TNF-α were decreased (P < 0.01). (ii) In vivo experiments, high dose of LBP significantly increased morphological changes in the outer nuclear layer (ONL) thickness of Rd10 mice, as well as functional changes in the amplitudes of the a-wave and b-wave (P < 0.01), which also down-regulated the expression levels of NF-κB (P < 0.05), NLRP3, p-NF-κB, and caspase-3 (P < 0.01), reduced the Bax/Bcl-2 rate (P < 0.01), and decreased the concentrations of IL-1β (P < 0.01) and TNF-α (P < 0.05). ConclusionLBP could improve both retinal morphology and function, providing protection to photoreceptors from apoptosis through the inhibition of the NF-κB/NLRP3 pathway.

REG1A protects retinal photoreceptors from blue light damage.

With the increased use of artificial light and the prolonged use of optoelectronic products, light damage (LD) to the human retina has been identified as a global vision-threatening problem. While there is evidence of a significant correlation between light-induced retinal damage and age-related vision impairment in age-related macular degeneration, it is unclear how light-induced retinal degeneration manifests itself and whether there are agents capable of preventing the development of LD in the retina. This study investigated a mechanism by which blue light leads to photoreceptor death. By observing blue light exposure in retinal organoids and photoreceptor cells, we concluded that there could be significant apoptosis of the photoreceptors. We demonstrate that regenerating islet-derived 1 alpha (REG1A) prevents photoreceptors from undergoing this LD-induced apoptosis by increasing expression of the anti-apoptotic gene Bcl2 and downregulating expression of the pro-apoptotic gene Bax, resulting in reduced mitochondrial damage and improved aerobic capacity in photoreceptor cells. For the first time, REG1A has been shown to restore mitochondrial function and cell apoptosis after LD-induced damage, suggesting its potential application in the prevention and treatment of retinal vision loss.